R_IsEGA() 
 Determines if an EGA card is present
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 Syntax
        lIsEGA := R_IsEGA ()

 Parameters
        (None)

 Returns
        lIsEGA          .T. :   EGA card is present or can be emulated
                        .F. :   No EGA card present

 Description
        This function can determine if the PC supports EGA.
        That might be important for the function R_ShowPCX ().

 Example
        IF R_IsEGA ()
                R_ShowPCX ( 'STANDEGA.PCX' )
                [...]
        ELSE
                Alert ( 'EGA adapter required to display this picture.' )

        ENDIF